In operation, both two and four-stroke cycle diesel engines generate what is known in the art as "blow-by gases", or combustion gases which during the compression and firing strokes of a piston blow past compression ring seals surrounding the piston, and subsequently down between a cylinder wall surface and a piston sidewall surface. In diesel engines powered by fuels containing abrasive particles, for example a coal-water slurry fuel, these blow-by gases contain abrasive particulate matter (for example, ashes).
When this abrasive particulate matter enters between the piston sidewall surface and the cylinder wall surface (or liner), it causes excessive wear of these surfaces and also of the compression ring seals. This excessive wear eventually causes premature failure of the diesel engine. Accordingly, it would be desirable to provide an improvement for diesel engines whereby dirt contained in the combustion gases is both prevented from entering and purged from between the piston sidewall surface and cylinder wall surface.